Heat transfer enhancement of phase change materials for thermal energy storage applications: A critical review
TL;DR: In this paper, the authors present a review on various techniques of heat transfer enhancement in latent heat thermal energy storage (LHTES) systems, which can be achieved through either geometric configuration and/or thermal conductivity enhancement.
Abstract: This paper presents a state-of-the-art review on various techniques of heat transfer enhancement in latent heat thermal energy storage (LHTES) systems. Heat transfer enhancement in LHTES systems can be achieved through either geometric configuration and/or thermal conductivity enhancement. The use of extended surfaces such as fins or heat pipes is a common technique for heat transfer enhancement in LHTES systems and therefore, reviewed in details in this paper. Next, we studied the thermal conductivity enhancement techniques, which include the use of porous materials, nanoparticles with high thermal conductivity, and low-density materials. Finally, studies involving combined techniques for heat transfer enhancement are reviewed in the paper. The paper discusses research gaps in the methods of heat transfer enhancement for LHTES systems and proposed some recommendations.
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TL;DR: In this article, the authors focus on the application of various phase change materials based on their thermophysical properties, in particular, the melting point, thermal energy storage density and thermal conductivity of the organic, inorganic and eutectic phases.
813 citations
TL;DR: In this article, the authors reviewed the methods for enhancing thermal conductivity of phase change materials (PCMs), which include adding additives with high thermal conductivities and encapsulating phase change material.
Abstract: In recent years, energy conservation and environmental protection have become most important issues for humanity. Phase change materials (PCMs) for thermal energy storage can solve the issues of energy and environment to a certain extent, as PCMs can increase the efficiency and sustainability of energy. PCMs possess large latent heat, and they store and release energy at a constant temperature during the phase change process. Thereby PCMs have gained a wide range of applications in various fields, such as buildings, solar energy systems, power systems and military industry. However, low thermal conductivity of PCMs leads to low heat transfer rate, thus, numerous studies have been carried out to improve thermal conductivity of PCMs. The main purpose of this paper is to review the methods for enhancing thermal conductivity of PCMs, which include adding additives with high thermal conductivity and encapsulating phase change materials. It is found that addition of thermal conductivity enhancement fillers is a more effective method to improve thermal conductivity of PCMs, where carbon-based material additives possess a more promising application prospect. Finally, the applications of PCMs in solar energy system, buildings, cooling system, textiles and heat recovery system are also analyzed.
538 citations
TL;DR: In this article, the authors assess the advantages/disadvantages of porous materials via summarizing the key research progress on the porous materials (e.g., metal foams, expanded graphite, graphene aerogels, carbon nanotubes, porous minerals, mesoporous silica, etc.) as ss-PCMs supports.
415 citations
TL;DR: In this paper, the effect of porosity and pore density on heat transfer, thermal conductivity, specific heat, latent heat and charging/discharging time are critically reviewed.
336 citations
TL;DR: In this article, a comparative review of phase change material (PCM) based LHS performance enhancement methods is presented, which can be classified into three categories: using high thermal conductivity additives and porous media to enhance PCM thermal conductivities, using finned tubes and encapsulated PCMs to extend heat transfer surface, using multistage or cascaded LHS technique and thermodynamic optimization to improve the heat transfer uniformity.
Abstract: Latent heat storage (LHS) is considered as the most promising technique for thermal energy storage, due to its high energy storage density and nearly constant working temperature. However, the lower thermal conductivity of the phase change material (PCM) used in LHS system seriously weakens thermal energy charging and discharging rates. In order to improve the thermal performance of LHS system, a lot of research on performance enhancement have been carried out. This review paper will concern on the development of PCMs and performance enhancement methods for LHS system in the last decade. The available enhancement methods can be classified into three categories: using high thermal conductivity additives and porous media to enhance PCM thermal conductivity, using finned tubes and encapsulated PCMs to extend heat transfer surface, using multistage or cascaded LHS technique and thermodynamic optimization to improving the heat transfer uniformity. The comparative reviews on PCMs, corresponding performance enhancement methods and their characteristics are presented in present paper. That will help in selecting reliable PCMs and matching suitable performance enhancement method to achieve the best thermal performance for PCM based LHS system. In addition, the research gaps in performance enhancement techniques for LHS systems are also discussed and some recommendations for future research are proposed.
327 citations
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TL;DR: The use of a latent heat storage system using phase change materials (PCMs) is an effective way of storing thermal energy and has the advantages of high energy storage density and the isothermal nature of the storage process.
Abstract: The use of a latent heat storage system using phase change materials (PCMs) is an effective way of storing thermal energy and has the advantages of high-energy storage density and the isothermal nature of the storage process. PCMs have been widely used in latent heat thermal-storage systems for heat pumps, solar engineering, and spacecraft thermal control applications. The uses of PCMs for heating and cooling applications for buildings have been investigated within the past decade. There are large numbers of PCMs that melt and solidify at a wide range of temperatures, making them attractive in a number of applications. This paper also summarizes the investigation and analysis of the available thermal energy storage systems incorporating PCMs for use in different applications.
4,482 citations
TL;DR: In this paper, a review of the history of thermal energy storage with solid-liquid phase change has been carried out and three aspects have been the focus of this review: materials, heat transfer and applications.
4,019 citations
TL;DR: In this paper, a review of the phase change materials (PCM) and their application in energy storage is presented, where the main advantages of encapsulation are providing large heat transfer area, reduction of the PCMs reactivity towards the outside environment and controlling the changes in volume of the storage materials as phase change occurs.
2,636 citations
TL;DR: In this paper, the phase change problem has been formulated using pure conduction approach but the problem has moved to a different level of complexity with added convection in the melt being accounted for, which makes it difficult for comparison to be made to assess the suitability of PCMs to particular applications.
Abstract: This paper reviews the development of latent heat thermal energy storage systems studied detailing various phase change materials (PCMs) investigated over the last three decades, the heat transfer and enhancement techniques employed in PCMs to effectively charge and discharge latent heat energy and the formulation of the phase change problem. It also examines the geometry and configurations of PCM containers and a series of numerical and experimental tests undertaken to assess the effects of parameters such as the inlet temperature and the mass flow rate of the heat transfer fluid (HTF). It is concluded that most of the phase change problems have been carried out at temperature ranges between 0 °C and 60 °C suitable for domestic heating applications. In terms of problem formulation, the common approach has been the use of enthalpy formulation. Heat transfer in the phase change problem was previously formulated using pure conduction approach but the problem has moved to a different level of complexity with added convection in the melt being accounted for. There is no standard method (such as British Standards or EU standards) developed to test for PCMs, making it difficult for comparison to be made to assess the suitability of PCMs to particular applications. A unified platform such as British Standards, EU standards needs to be developed to ensure same or similar procedure and analysis (performance curves) to allow comparison and knowledge gained from one test to be applied to another.
1,630 citations
TL;DR: In this article, the authors summarized previous works on latent thermal energy storage in building applications, covering PCMs, the impregnation methods, current building applications and their thermal performance analyses, as well as numerical simulation of buildings with PCMs.
1,569 citations